Package dependencies not installed on first `uv run --extra` with conflicting extras

[eginhard]

I can confirm that #9533 is fixed with uv 0.5.6, this is a follow-up for packages with dependencies in conflicting extras:

[project]
name = "project"
version = "0.1.0"
requires-python = ">=3.10.0"
dependencies = []

[project.optional-dependencies]
cpu = ["torch>=2.0"]
cu118 = ["torch>=2.0"]

[tool.uv]
conflicts = [
  [
    { extra = "cpu" },
    { extra = "cu118" },
  ],
]

[tool.uv.sources]
torch = [
  { index = "pytorch-cpu", extra = "cpu", marker = "platform_system != 'Darwin'" },
  { index = "pytorch-cu118", extra = "cu118" },
]

[[tool.uv.index]]
name = "pytorch-cpu"
url = "https://download.pytorch.org/whl/cpu"
explicit = true

[[tool.uv.index]]
name = "pytorch-cu118"
url = "https://download.pytorch.org/whl/cu118"
explicit = true

To reproduce:

1. Ensure lock file and venv are not present:

rm .venv/ uv.lock -rdf

2. On the first run only torch itself is installed:

$ uv run --extra cpu python -c "import torch; print(torch.__version__)"
Using CPython 3.13.0
Creating virtual environment at: .venv
Installed 1 package in 88ms
Traceback (most recent call last):
  File "<string>", line 1, in <module>
    import torch; print(torch.__version__)
    ^^^^^^^^^^^^
  File ".../.venv/lib/python3.13/site-packages/torch/__init__.py", line 37, in <module>
    from typing_extensions import ParamSpec as _ParamSpec, TypeGuard as _TypeGuard
ModuleNotFoundError: No module named 'typing_extensions'

3. The dependencies only get installed on the second run:

$ uv run --extra cpu python -c "import torch; print(torch.__version__)"
Installed 9 packages in 16ms
2.5.1+cpu

[charliermarsh]

Should be fixed soon, sorry about that.